Python - pandas - datetime

import pandas as pd

df = pd.DataFrame({
    'time': ['00:00:01', '00:01:00', '01:00:00'],
    'datetime': ['2018.06.29 00:00:01', '2018.06.29 00:01:00', '2018.06.29 01:00:00'],
})

print('time:', df['time'].dtypes)
print('datetime:', df['datetime'].dtypes)

df['time'] = pd.to_datetime(df['time'], format='%H:%M:%S')
df['datetime'] = pd.to_datetime(df['datetime'], format='%Y.%m.%d %H:%M:%S')

print('time:', df['time'].dtypes)
print('datetime:', df['datetime'].dtypes)

print(df)